Authentication using prism

ABSTRACT

A prism of an approximately quadrangle-frustum shape is arranged so that a bottom side, out of two parallel surfaces of the prism, is a placing surface side for a finger. A first imaging unit arranged below a top surface parallel to the bottom surface images an image of the finger transmitted through the top surface. A light source radiates light to at least one side surface of a first set of side surfaces, out of two sets of side surfaces of the approximately quadrangle-frustum shape that face each other. A second imaging unit images the image of the finger transmitted through a second set of side surfaces, out of the two sets of side surfaces. An infrared ray light source radiates infrared ray light into the finger so that the infrared ray light is scattered inside the finger and is received by the imaging unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 17/229,009 filed on Apr. 13, 2021, which is acontinuation application of U.S. patent application Ser. No. 16/124,914filed on Sep. 7, 2018, which is a continuation application of U.S.patent application Ser. No. 15/854,217 filed on Dec. 26, 2017, which isa continuation application of U.S. patent application Ser. No.14/007,177 filed on Sep. 24, 2013, which is a National Stage Entry ofinternational application PCT/JP2012/057346, filed on Mar. 22, 2012,which claims the benefit of priority from Japanese Patent Application2011-068705 filed on Mar. 25, 2011, the disclosures of all of which areincorporated in their entirety by reference herein.

TECHNICAL FIELD

The present invention relates to an authentication apparatus and anauthentication method.

BACKGROUND ART

The apparatus for determining a subject as a forged finger when thecolor of the image acquired by reflecting visible light offorgery-determining illumination on the subject does not coincide withthat of the finger image that has been acquired likewise and has beenpreviously registered in a data storing means is described in Patentliterature 1. The same apparatus collates a characteristic pointobtained from the transmitted light by radiating near-infrared ray ofindividual identification illumination to the finger with thecharacteristic point of the finger image that has been acquired likewiseand has been previously registered into the data storing means, andperforms the individual identification.

The apparatus for selectively switching white light and infrared light,reflecting the white light on a surface layer portion of the fingerthereby to acquire the fingerprint image, making the infrared rayincident inside the finger and scattering the infrared ray thereby toacquire a vein image, comparing the fingerprint image and the vein imagewith the registered fingerprint image and the registered vein image,respectively, and authenticating a specific personal is described inPatent literature 2.

The apparatus for comparing the fingerprint image with high sensitivitywith the fingerprint image with low sensitivity, and determining theforged finger is described in Patent literature 3.

The apparatus for, based on a difference of the finger vein imagesimaged with the transmitted lights having a different wavelength,determining whether the above finger vein image is the finger vein imageof a living body is described in Patent literature 4.

On the other hand, the technique of using a prism as a scanner for thefingerprint authentication, and augmenting a contrast is described inPatent literature 5.

CITATION LIST Patent Literature

-   PTL 1: JP-P2007-122237A-   PTL 2: JP-P2007-179434A-   PTL 3: JP-P2007-259964A-   PTL 4: JP-P2008-67727A-   PTL 5: U.S. Pat. No. 6,381,347

SUMMARY OF INVENTION Technical Problem

By the way, in recent years, it is difficult to see through the actionsuch as “impersonating” others by affixing a semi-transparent forgedfilm of the finger having concave and convex to the tip of the genuinefinger. Such a malicious action is also done by use of the finger forgedwith resin such as silicon having concave and convex.

However, any of the above-described Patent literatures 1 to 4 cannotdetect the forgery of the above finger at a high precision using thereflected light image and the transmitted light image that are obtainedfrom the identical finger.

Further, the technology of the Patent literature 5 as well can obtainthe image with a high contrast necessary for the collation of thefingerprint; however, the Patent literature 5 cannot detect the forgeryof the finger at a high precision similarly to the technologies of theabove-described Patent literatures 1 to 4 because only the image of theportion having contacted the prism is obtained.

Thereupon, the present invention has been accomplished in considerationof the above-mentioned problems, and an object of the present inventionis to provide an authentication apparatus and an authentication methodcapable of acquiring the fingerprint image having a contrast enough forcollating the fingerprint and a natural image of the finger that isclose to visibility.

Solution to Problem

The present invention is an authentication apparatus comprising: a prismof an approximately quadrangle-frustum shape, said prism of theapproximately quadrangle-frustum shape is arranged so that a bottomside, out of two parallel surfaces of said prism of approximatelyquadrangle-frustum shape, is a placing surface side for a finger; afirst imaging means is arranged below a top surface parallel to saidbottom surface, said first imaging means that images an image of thefinger transmitted through said top surface; a light source thatradiates light to at least one side surface of a first set of sidesurfaces, out of two sets of side surfaces of said approximatelyquadrangle-frustum shape that face each other; and a second imagingmeans that images the image of the finger transmitted through a secondset of side surfaces, out of said two sets of side surfaces.

The present invention is an authentication method comprising: arranginga prism of an approximately quadrangle-frustum shape so that a bottomside, out of two parallel surfaces of the approximatelyquadrangle-frustum shape, is a placing surface side for a finger;radiating light from at least one side surface of a first set of sidesurfaces, out of two sets of side surfaces of said approximatelyquadrangle-frustum shape that face each other; and from a lower part ofa top surface parallel to said bottom surface, imaging an image of thefinger transmitted through said top surface; imaging the image of thefinger transmitted through a second set of side surfaces, out of saidtwo sets of side surfaces; and simultaneously imaging a natural image ofthe finger and the image of a fingerprint portion.

Advantageous Effect of Invention

The present invention makes it possible to acquire the fingerprint imagehaving a contrast enough for collating the fingerprint and the naturalimage that is close to visibility.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a top view of a living body authentication apparatus in afirst exemplary embodiment.

FIG. 2 is a cross-sectional view of M-N of the living bodyauthentication apparatus.

FIG. 3 is a cross-sectional view of X-Y of the living bodyauthentication apparatus.

FIG. 4 is a view for explaining a regular quadrangle-frustum shape typeprism 10 to be used for the living body authentication apparatus of thefirst exemplary embodiment.

FIG. 5 is a view for explaining the first exemplary embodiment.

FIG. 6 is a view for explaining the first exemplary embodiment.

FIG. 7 is a cross-sectional configuration view of the authenticationapparatus in a second exemplary embodiment.

FIG. 8 is a cross-sectional configuration view of the authenticationapparatus in the second exemplary embodiment.

DESCRIPTION OF EMBODIMENTS

The exemplary embodiments of the present invention will be explained.

Each of FIG. 1 , FIG. 2 , and FIG. 3 is a view for explaining the livingbody authentication apparatus in the first exemplary embodiment, FIG. 1is a top view of the living body authentication apparatus in the firstexemplary embodiment, FIG. 2 is a cross-sectional view of M-N of theliving body authentication apparatus, and FIG. 3 is a cross-sectionalview of X-Y of the living body authentication apparatus.

The regular quadrangle-frustum shape type prism 10 is arranged into aliving body authentication apparatus 1 of the first exemplaryembodiment.

FIG. 4 is a view for explaining the regular quadrangle-frustum shapetype prism 10 to be used for the living body authentication apparatus ofthe first exemplary embodiment. The regular quadrangle-frustum shapetype prism 10 is arranged so that one surface a (bottom surface (surfacehaving a larger area)), out of two parallel plate-shape surfaces a andb, is a placing surface of the fingerprint. Additionally, an example ofdefining the type of the prism 10 as the regular quadrangle-frustumshape type prism is explained in the first exemplary embodiment;however, the shape may be changed without departing from the spirit andscope of the invention.

Further, a first imaging unit 11 that images the image of a finger 2transmitted through the surface b (top surface (surface having a smallerarea) of the prism 10 is arranged in the lower part of the surface b ofthe prism 10. As the imaging unit 11, which converts the inputted imageinto a digital signal and outputs it, an image sensor comprised of CCD,or CMOS etc. can be also used. This imaging unit 11 images the naturalimage of the finger by the light transmitted through the surface b ofthe prism 10, and obtains the image for determining the forged finger.

Light sources 13 and 14 that radiate the light to the fingerprintportion of the finger 2 are installed in the side surfaces c and d sidesof the prism 10 that face each other, respectively. These light sources13 and 14 are white LEDs emitting visible light, for example, the whitelight, and the like.

Further, in one side surface e side, out of side surfaces e and f of theprism 10 that face each other, a second imaging unit 12 that images thefinger portion of the finger 2 transmitted through the side surface e isarranged. As the imaging unit 12, which converts the inputted image intoa digital signal and outputs it, an image sensor comprised of CCD, orCMOS etc. can be also used. This imaging unit 12 images the fingerprintcollation image of the fingerprint portion of the finger 2 having a highcontrast (a mountain and a valley of the fingerprint are clear) by thelight transmitted through the side surface e.

On the other side, a black shielding plate 15 that does not allow thelight to be transmitted is installed in the surface f. This shieldingplate 15 allows the fingerprint collation image imaged by the imagingunit 12 to become an image with a higher contrast. Additionally, in thisexemplary embodiment, the black shielding plate 15 was installed in thesurface f; however, the outer surface of the surface f of the prism 10may be pained in a block color.

Next, an operation of the above-mentioned living body authenticationapparatus will be explained.

At first, the finger 2 is placed on the surface a of the prism 10, beinga placing surface, at the moment of the authentication.

The light sources 13 and 14 emits the light in a situation in which thefingerprint portion of the finger 2 is placed on the surface a of theprism 10, and radiates the light for photography to the surfaces c and dof the prism 10, respectively.

The imaging unit 11 images the natural image of the finger by the lighttransmitted through the surface b of the prism 10. One example of theimage imaged by the imaging unit 11 is shown in FIG. 5 . As apparentfrom FIG. 5 , it can be grasped that the natural image of the finger 2including the fingerprint portion is imaged. Displaying the image imagedby this imaging unit 11 on a display device, and visually confirming itmakes it possible to determine whether a fingerprint film, a tape andthe like forged at the moment of the collation have been used.

On the other hand, the imaging unit 12 images the image of thefingerprint portion of the finger 2 by the light transmitted through thesurface e. One example of the image imaged by the imaging unit 12 isshown in FIG. 6 . As apparent from FIG. 6 , it can be grasped that theimage of the fingerprint portion having a high contrast (a mountain anda valley of the fingerprint are clear) has been photographed. Performingthe extraction/collation of a characteristic quantity from the imageimaged by this imaging unit 12 makes it possible to collate andauthenticate the fingerprint.

In such a manner, the authentication apparatus of the first exemplaryembodiment can obtain the natural image close to the visibility fordetermining whether the forged fingerprint film and tape, and the likehave been used, and the image having a high contrast to be used forcollating the fingerprint with one-time photography of the finger.

Second Exemplary Embodiment

The second exemplary embodiment will be explained.

FIG. 7 is a cross-sectional configuration view of the authenticationapparatus in the second exemplary embodiment.

In the second exemplary embodiment, an example of installing an infraredray light source 20 in addition to the configuration of the firstexemplary embodiment, and imaging the fingerprint image by the lightthat scatters inside the finger, and is transmitted will be explained.

In the second exemplary embodiment, the infrared ray light source 20 isarranged in the authentication apparatus. The infrared ray light source20 is arranged on a shielding plate 21 so that the infrared-ray lightdoes not enter the prism 10 if possible. Further, an infrared raytransmission filter 22 is i arranged in the imaging unit 12. Making sucha configuration enables the imaging unit 12 to image the image of thefingerprint portion with a high contrast (a mountain and a valley of thefingerprint are clear) as compared with the image imaged only by lightsources 13 and 14 such as the while light etc.

In addition, as shown in FIG. 8 , an infrared ray light source 24 forirradiating a root portion of the finger 2 may be arranged in additionto the infrared ray light source 20. Installing the infrared ray lightsource 24 for irradiating the root portion of the finger 2 makes itpossible to obtain the image of the fingerprint portion that is brightalso in a root side of the fingerprint. Additionally, the infrared lightis absorbed with hemoglobin of blood, whereby a blood vessel pattern ofthe finger 2 can be also imaged.

In order to photograph the natural image for determining whether theforged fingerprint film and tape, and the like have been used, aninfrared ray cut-off filter 23 is arranged in the imaging unit 11. Withregard to the lights incident on the imaging unit 11, the infrared rayis cut off by the infrared ray cut-off filter 23, and the imaging unit11 can image the natural image of the fingerprint portion of the finger2 by the visible light owing to the light sources 13 and 14.

In accordance with the second exemplary embodiment, the fingerprintimage having a high contrast by the light that scatters inside thefinger due to the infrared light source and is transmitted in additionto the effect of the first exemplary embodiment can be obtained.Further, a pulse beat caused by a blood flow and a change in the imagedue to a subcutaneous tissue are also can be observed, and the livingbody determination with a higher precision can be also performed byusing it for the living body determination.

Further, the content of the above-mentioned exemplary embodiments can beexpressed as follows.

(Supplementary note 1) An authentication apparatus comprising:

a prism of an approximately quadrangle-frustum shape, said prism of theapproximately quadrangle-frustum shape is arranged so that a bottomside, out of two parallel surfaces of said prism of approximatelyquadrangle-frustum shape, is a placing surface side for a finger;

a first imaging means is arranged below a top surface parallel to saidbottom surface, said first imaging means that images an image of thefinger transmitted through said top surface;

a light source that radiates light to at least one side surface of afirst set of side surfaces, out of two sets of side surfaces of saidapproximately quadrangle-frustum shape that face each other; and

a second imaging means that images the image of the finger transmittedthrough a second set of side surfaces, out of said two sets of sidesurfaces.

(Supplementary note 2) The authentication apparatus according toSupplementary note 1, wherein said prism is a regularquadrangle-frustum.

(Supplementary note 3) The authentication apparatus according toSupplementary note 1 or Supplementary note 2, wherein a black plate isinstalled in the side surface facing the side surface to be arranged insaid second imaging means, out of said second sets of side surfaces ofsaid prism, or an color of an outer surface of said side surface isblack.

(Supplementary note 4) The authentication apparatus according to one ofSupplementary note 1 to Supplementary note 3, comprising:

an infrared light source that radiates infrared ray light to a cushionportion of the finger;

an infrared ray cut-off filter that cuts off the infrared ray lightincident on said first imaging means; and

a visible light cut-off filter that cuts off visible light incident onsaid second imaging means.

(Supplementary note 5) An authentication method comprising:

arranging a prism of an approximately quadrangle-frustum shape so that abottom side, out of two parallel surfaces of the approximatelyquadrangle-frustum shape, is a placing surface side for a finger;

radiating light from at least one side surface of a first set of sidesurfaces, out of two sets of side surfaces of said approximatelyquadrangle-frustum shape that face each other; and

from a lower part of a top surface parallel to said bottom surface,imaging an image of the finger transmitted through said top surface;

imaging the image of the finger transmitted through a second set of sidesurfaces, out of said two sets of side surfaces; and

simultaneously imaging a natural image of the finger and the image of afingerprint portion.

(Supplementary note 6) The authentication method according toSupplementary note 5, wherein said prism is regular quadrangle-frustum.

(Supplementary note 7) The authentication method according toSupplementary note 5 or Supplementary note 6, comprising enhancing acontrast of the image of the fingerprint portion by installing a blackplate in the surface of the side facing the surface side in which theimage is imaged, out of said second sets of side surfaces of said prism,or making an color of an outer surface of said side surface black.

(Supplementary note 8) The authentication method according to one ofSupplementary note 5 to Supplementary note 7, comprising:

radiating visible light from at least one side surface of the first setof side surfaces, out of two sets of side surfaces of said approximatelyquadrangle-frustum shape that face each other,

radiating infrared ray light to a cushion portion of the finger;

cutting off the infrared ray light, out of transmitted lights that aretransmitted through an top surface parallel to said bottom surface, andimaging the natural image of the finger by the visible light; and

cutting off the visible light, out of transmitted lights that aretransmitted through the second set of side surfaces, out of said twosets of side surfaces, and imaging the image of the fingerprint portionof the finger by the infrared ray light.

Above, although the present invention has been particularly describedwith reference to the preferred embodiments, it should be readilyapparent to those of ordinary skill in the art that the presentinvention is not always limited to the above-mentioned embodiments, andchanges and modifications in the form and details may be made withoutdeparting from the spirit and scope of the invention.

This application is based upon and claims the benefit of priority fromJapanese patent application No. 2011-068705, filed on Mar. 25, 2011, thedisclosure of which is incorporated herein in its entirety by reference.

REFERENCE SIGNS LIST

-   -   1 living body authentication apparatus    -   10 prism    -   11 and 12 imaging units    -   13 and 14 light sources    -   15 shielding plate    -   20 and 24 infrared ray light sources    -   21 shielding plate    -   22 infrared ray transmission filter    -   23 infrared ray cut-off filter

1. An authentication apparatus comprising: a prism arranged so that abottom surface, out of two parallel surfaces of the prism, is a placingsurface side for a finger; a first imaging sensor arranged below a topsurface parallel to the bottom surface, and the first imaging sensorconfigured to image an image of the finger transmitted through the topsurface; a second imaging sensor configured to image the image of thefinger transmitted through a first set of side surfaces, out of two setsof side surfaces that face each other; an inclined part having contactedthe prism; a light-shielding portion provided with the inclined part; afirst infrared light source arranged in the light-shielding portion forirradiating first infrared ray light to a root portion of the finger;and a second infrared light source arranged opposite to the firstinfrared light source with respect to the prism for radiating secondinfrared ray light to a portion of the finger that is not in contactwith the placing surface of the finger, wherein the inclined part isinclined toward the bottom surface of the prism so that a height of theinclined part decreases as a distance from the prism becomes larger, thefirst infrared light source is arranged on a shielding plate so that thefirst infrared ray light from the first infrared light source does notenter the prism, the second image sensor receives the first infrared raylight and the second infrared ray light transmitted from the firstinfrared light source and the second infrared light source through thefirst set of side surfaces, and captures a blood vessel image of thefinger, and it is determined whether or not the finger is a living bodybased on the blood vessel image.
 2. The authentication apparatusaccording to claim 1, further comprising: a light source configured toirradiate infrared ray light to at least one side surface of a secondset of side surfaces, out of the two sets of side surfaces that faceeach other.
 3. The apparatus according to claim 1, wherein the prismincluding a first surface for placing a finger, a second surface smallerthan the first surface, a first inclined lateral surface, a secondinclined lateral surface, a third inclined lateral surface, and a fourthinclined lateral surface, the apparatus further comprising: a blackplate is installed in the fourth inclined lateral surface facing thesecond inclined lateral surface, or a color of an outer surface of thefourth inclined lateral surface facing the second inclined lateralsurface is black.
 4. An authentication method using apparatus whichcomprises: a prism arranged so that a bottom surface, out of twoparallel surfaces of the prism, is a placing surface side for a finger;a first imaging sensor arranged below a top surface parallel to thebottom surface, and the first imaging sensor configured to image animage of the finger transmitted through the top surface; a secondimaging sensor configured to image the image of the finger transmittedthrough a first set of side surfaces, out of two sets of side surfacesthat face each other; an inclined part having contacted the prism; alight-shielding portion provided with the inclined part; a firstinfrared light source arranged in the light-shielding portion forirradiating first infrared ray light to a root portion of the finger;and a second infrared light source arranged opposite to the firstinfrared light source with respect to the prism for radiating secondinfrared ray light to a portion of the finger that is not in contactwith the placing surface of the finger, wherein the inclined part isinclined toward the bottom surface of the prism so that a height of theinclined part decreases as a distance from the prism becomes larger, thefirst infrared light source is arranged on a shielding plate so that thefirst infrared ray light from the first infrared light source does notenter the prism, the method comprising: receiving, by the second imagesensor, the first infrared ray light and the second infrared ray lighttransmitted from the first infrared light source and the second infraredlight source through the first set of side surfaces to capture a bloodvessel image of the finger, and determining whether or not the finger isa living body based on the blood vessel image.
 5. A non-transitorycomputer readable medium recording a program that causes anauthentication method using apparatus which comprises: a prism arrangedso that a bottom surface, out of two parallel surfaces of the prism, isa placing surface side for a finger; a first imaging sensor arrangedbelow a top surface parallel to the bottom surface, and the firstimaging sensor configured to image an image of the finger transmittedthrough the top surface; a second imaging sensor configured to image theimage of the finger transmitted through a first set of side surfaces,out of two sets of side surfaces that face each other; an inclined parthaving contacted the prism; a light-shielding portion provided with theinclined part; a first infrared light source arranged in thelight-shielding portion for irradiating first infrared ray light to aroot portion of the finger; and a second infrared light source arrangedopposite to the first infrared light source with respect to the prismfor radiating second infrared ray light to a portion of the finger thatis not in contact with the placing surface of the finger, wherein theinclined part is inclined toward the bottom surface of the prism so thata height of the inclined part decreases as a distance from the prismbecomes larger, the first infrared light source is arranged on ashielding plate so that the first infrared ray light from the firstinfrared light source does not enter the prism, the method comprising:receiving, by the second image sensor, the first infrared ray light andthe second infrared ray light transmitted from the first infrared lightsource and the second infrared light source through the first set ofside surfaces to capture a blood vessel image of the finger, anddetermining whether or not the finger is a living body based on theblood vessel image.